<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
   <!-- <script src="https://cdn.bootcss.com/vue/2.2.2/vue.min.js"></script>-->
</head>
<body>
<div id="app">
    <input type="text" v-model="msg">
    {{msg}}
</div>
</body>
<script>
   /* var ym = new Vue({
        el: '#app',
        data:{ msg:'aaaa'}
        });
*/

    function  V(obj) {
        for (var p in  obj){
            if (p=='el'){
                this['$'+p] = document.querySelector(obj[p]);
            }else if (p == 'data'){
                this['$'+p] = obj[p];
                for(var q in  obj[p]){
                    this[q] = obj[p][q];
                }
            }
        }
    }
    var V = new  V({
        el:'#app',
        data:{
            msg:'aaaa'
        }
    });
</script>
</html>